New Sansa Clip + Refurb - sound problem

I recently purchased a Sansa Clip + refurb from eBay and although it looks in great condition, there is a problem with the sound.

It's as if you only hear some of the instruments, like certain layers of the sounds. Definitely not a problem with the files (tried mp3 128, 320, wma and FLAC) but all have the same playback problem. I have tried 3 different headphones that work fine with other devices so it's not the headphones either. Tried a firmware update, format, installed RockBox, tried everything!

I thought it could be a loose jack but i have tried wiggling the headphone cable and twisting it but it makes no difference. The headphone fits into the player fine and it's pressed in as far it will go. I'm getting sound through both left and right headphones, just only hearing some of the music.

I have opened the player up and the headphone jack barely moves. Could the jack be faulty? Is it possible to replace it? If so, do i need a specific headphone jack or anything that has 3 pins? Do SanDisk sell the headphone jacks? (longshot i know)

The seller has no more in stock and has give me a refund and told me i can keep it so i can't replace it but is there anything i can try to fix it as i really wanted to try usng this legendary MP3 player.